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Six reasons why Photonics and Optics are important for the future!

Our modern day electronic devices are based on transistors and other semiconductor devices. Moore’s law has proved to be nearly accurate as we develop better and smaller circuits having more number of transistors per square inch. However, there will be a time maybe after two decades (as predicted by Moore himself) where we may not be able to make any further development with the integrated circuit based devices.

The future computing devices, be it quantum computers(1) or for that matter even simple photonic integrated circuits(2), have already given us a new perspective to the power and versatility of computation in the future. With the ever increasing demand for faster and more efficient computing, photonics seems to be a promising candidate. Technology giants such as Intel(3), IBM(4) and Google already have made huge investments in this direction. Wearable technology like the Google Glass(5) and Microsoft’s Hololens(6) have shown how we can use light to connect our digital world to our lives. So all we can expect is a better and a more interactive computing experience in the future.(7)(8)

A multidirectional `perfect paraxial’ cloak using 4 lenses. For a continuous range of viewing angles, the hand remains cloaked, and the grids seen through the device match the background on the wall (about 2 m away), in color, spacing, shifts, and magnification. The edges of the optics can be seen since this is a small-angle (‘paraxial’) cloak, but this can be reduced by using large optics and for distant viewing; also the center of the device must not be blocked. Credit: J. Adam Fenster / University of Rochester

Metamaterials

Metamaterials are artificial, precision-engineered materials which can exhibit peculiar properties not found in natural materials which makes them interesting! Eminent scientists like Jagdish Chandra Bose[9], Victor Veselago(10) and Winston Kock(11) had predicted and modeled such artificial materials in electromagnetics, wave interactions and mechanics. However their true potential was realized only after they were fabricated at the end of the 20th century(12). One of the hot topics in metamaterial research and a simple applications to manufacture metamaterial cloaks(13) (like the one Harry Potter had) to prevent from being sighted. As of now, there are no optical metamaterials that cover the entire visible range of the spectrum however there has been considerable progress with microwaves. Costly fabrication techniques have been an obstacle to metamaterial research. Metamaterials are predicted to be of great use particularly in defence applications to impart stealth and conceal units. Other applications of metamaterials include superlenses which are lenses that are almost free of aberrations and that can focus images below the diffraction limit.(14) We can expect better antennas and other devices based on metamaterials in our mobile phones in the future.(15)

Imaging

Imaging allows us to see the various physical and chemical changes taking place in a system. With the first camera-like device referred to as camera obscura to the modern day DSLRs, our cameras and imaging systems have changed drastically. Imaging plays a crucial role particularly in life science(16), medicine and security issues but is also important in many fields of physics and chemistry. Imaging with super-high frame rates has given us a way to study ultrafast phenomena like chemical and electron transfer reactions that occur in an infinitesimally small duration of time. This has been achieved with the help of pulsed femtosecond lasers which allow us to carry out pump-probe studies for repetitive events and also burst mode studies for non-repetitive events. Some famous ultrafast imaging systems for both repetitive and non-repetitive events are – the streak camera dubbed as Femto-photography(17), STEAM(18), STAMP(19), etc. Fingerprinting is the underlying concept for spectroscopy. Scanning devices at airports and other important locations for safety measures are based on such spectroscopic systems. We can expect cheaper, safer and faster imaging systems based on Terahertz radiation. Terahertz waves are electromagnetic waves which fall between the visible spectrum (1015 Hz) and high radio frequency waves (1010 Hz). Today we have high resolution cameras having as many as millions of pixels embedded in our smartphones to give us sharp images! Maybe in the future, we can have single pixel based efficient and smaller cameras which not only capture the visible spectrum but also infrared radiations.

The importance of light in material processing was understood after the development of photography. Since then laser-cutting of metallic blocks in the industry and various other processes were developed. Today, material processing using light has become highly sophisticated. 3D printing has been used so widely and in unimaginable ways(20). Nanofabrication and material processing at the nanoscale are very important not only for basic research but also for industrial applications. Structured hydrophobic surfaces which are based on the lotus leaf model have been demonstrated using femtosecond laser pulses on metals.(21) Optical data storage has been revolutionized and new technologies like the BluRay disc™ (22) have shown an almost 36 fold increase in data storage compared to the conventional Compact Discs of the same size. The conventional electron beam lithography used for making electronic devices at the nanoscale maybe someday replaced by an optical nanofabrication(23) technique which is diffraction limited that is the minimum feature size depends on the wavelength of light used. Optical techniques are faster, portable and enable us to design 3D free standing structures like nanowires!(24)

Energy & Communication

With the need for better renewable sources of energy, solar cells have demonstrated their mettle. Newer and newer designs based on bandgap engineering allow us to utilize the solar spectrum in the most efficient way and in the process avoiding damage to the cell. Moreover, detailed study of photosynthesis and light-matter interactions may someday allow us to fabricate the most efficient energy harvesting devices(25)(26). This will help us solve our energy crisis and up to some extent thwart deterioration of our environment. Trapping solar energy in space and wirelessly transporting it to earth using lasers has also been proposed by NASA, JAXA etc.(27)(28) This approach is called Space-based Solar Power. We have already seen how wireless charging has made our lives hassle-free. MIT Professor Marin Soljačić had started WiTricity® Corporation(29) which has developed and patented Highly Resonant Wireless Power Transfer technology which uses electromagnetic waves for transferring power wirelessly. Li-Fi (30)(31) (light based communication) is another idea which will give us an edge over the existing radio wave communication systems. Simple LED’s could be used as transmitters in this technique. With light we have more bandwidth and we can use division multiplexing techniques to send more information over the same channel. Use of entangled photon pairs for highly secure communication is another interesting future prospect for important online transactions.(32)

Basic Sciences and Research

Last but not the least, I personally believe that there is a lot of scope for research and development in optics and photonics. Since the development of the first laser, we have seen so much of technological advancement in this field.The interdisciplinary nature of this science is bound to amaze us in the future! In the past few years, we have seen some great advancements like self-accelerating light beams(33) which have interesting properties like self-healing(34) and curved trajectories.(35) Also, a lot of research on plasmonics has allowed us to think for newer optical devices.(36) The ability to squeeze light(37), slow it down(38), and impart angular momentum to it and the ability to cool macroscopic objects with the help of light are some of the cool applications developed in the last few decades. Who knows what these photons have in store to amaze us!

Abhijeet Phatak is a final year undergraduate student at the Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, India (www.iitbhu.ac.in). His research interests include optics, photonics, materials science, ceramic materials, nanotechnology, semiconductors, energy, metamaterials, quantum effects, computational physics and other sciences. Pursuing further research, he wishes to do something that will have a great and positive impact on the society.